DISSERTATION RESEARCH: Environmental Quality and the Costs of Reproduction: an Experimental Test in a Cooperatively Breeding Bird

生物体面临着一个根本性的决定：是将宝贵的资源和能量投入到繁殖中，还是投资于自身的生存。因此，繁殖可能导致存活率降低，这种关系被称为“繁殖成本”。对于一些生物来说，繁殖的成本被认为是如此之高，以至于父母在没有额外帮助的情况下无法繁殖。归根结底，这可能就是为什么一些物种生活在复杂的家庭群体中，或合作繁殖的社会中，个人组成社会群体来抚养他人的后代。为年轻人寻找食物是困难的，但如果个体聚集在一起寻找食物，繁殖成本就会降低。研究人员正在研究合作繁育鸟类，以确定繁殖成本是否有助于在家庭群体中饲养幼鸟。这个项目专门探讨繁殖过程中可用的资源如何增加或减少繁殖成本，并改变群体动态。这项研究还将为当地的肯尼亚外勤助理设立两个职位，并为一名女本科生提供指导，该女本科生将协助收集数据并进行独立项目。作为热带生物学海外学期的一部分，结果将与美国和肯尼亚的本科生分享。这项研究还将通过参加基层莱基皮亚保护俱乐部与来自农村小学的肯尼亚学生分享。研究人员将通过在合作繁殖物种--超级八哥的巢中添加昆虫来控制领土质量，以检查环境条件是否会导致繁殖成本。在雏鸟饲养之前和过程中都会捕捉到鸟类，以观察繁殖过程中发生的生理变化。之前对这一系统的研究表明，随着养鸡努力的增加，氧化应激增加，这是一个强有力的候选措施，可能会将繁殖努力与降低存活率联系起来。研究人员将研究食物补充如何改变这些生理变化的幅度，以推断资源的可获得性如何推动生殖成本。样本和数据将存储在哥伦比亚大学，并在出版后通过Dryad公开提供，Dryad是一个进化和生态数据的公共数据库。

Organisms are faced with a fundamental decision: to invest valuable resources and energy in reproduction or in their own survival. As a result, reproduction may lead to lowered survival, a relationship called the "cost of reproduction." For some organisms, the cost of reproduction is thought to be so high that parents cannot reproduce without additional help. Ultimately, this may be why some species live in complex family groups, or cooperatively breeding societies, where individuals form social groups to raise others' offspring. Finding food for the young is difficult, but if individuals come together to find food the cost of reproduction is lowered. The researchers are studying cooperatively breeding birds to determine whether the cost of reproduction promotes rearing young in family groups. This project specifically explores how resources available during reproduction can increase or decrease the cost of reproduction and alter group dynamics. This research will also create two positions for local Kenyan field assistants, and provide mentoring to a female undergraduate student who will assist with data collection and pursue an independent project. Results will be shared with US and Kenyan undergraduate students as part of a semester abroad in Tropical Biology. This research will also be shared with Kenyan students from rural elementary schools through participation in the grassroots Laikipia Conservation Clubs. Researchers will manipulate territory quality through an insect supplementation at nests of a cooperatively breeding species, the superb starling (Lamprotornis superbus), to examine whether environmental conditions drive the cost of reproduction. Birds will be caught both before and during chick rearing to look at the physiological changes that occur as a result of reproduction. Previous research in this system has indicated that oxidative stress increases with greater chick-rearing effort, a strong candidate measure that may link reproductive effort to reduced survival. The researchers will examine how food supplementation alters the magnitude of these physiological changes to infer how resource availability drives the cost of reproduction. Samples and data will be stored at Columbia and made publically available post publication through Dryad, a public data repository for evolutionary and ecological data.